Evidence of local and global scaling regimes in thin films deposited by sputtering: An atomic force microscopy and electrochemical study

The surface morphology of NiOx thin films deposited by rf sputtering was studied by atomic force microscopy and by cyclic voltammetry. Linear relationships were observed in log–log plots of the interface width versus window length and in log–log plots of the peak current versus scan rate. Two different slopes were observed, by both techniques, indicating that distinct growth dynamics present in the system can be measured in different ways. Moreover, the calculated fractal dimensions are in excellent agreement: the local scaling regime corresponds to high scan rates and the global scaling regime corresponds to low scan rates, in accordance with the expected behavior for diffusion fronts.